/*
 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
package java.awt;

import java.io.*;
import java.lang.*;
import java.util.*;
import java.awt.image.ImageObserver;
import java.text.AttributedCharacterIterator;

/**
 * The <code>Graphics</code> class is the abstract base class for
 * all graphics contexts that allow an application to draw onto
 * components that are realized on various devices, as well as
 * onto off-screen images.
 * <p>
 * A <code>Graphics</code> object encapsulates state information needed
 * for the basic rendering operations that Java supports.  This
 * state information includes the following properties:
 *
 * <ul>
 * <li>The <code>Component</code> object on which to draw.
 * <li>A translation origin for rendering and clipping coordinates.
 * <li>The current clip.
 * <li>The current color.
 * <li>The current font.
 * <li>The current logical pixel operation function (XOR or Paint).
 * <li>The current XOR alternation color
 * (see {@link Graphics#setXORMode}).
 * </ul>
 * <p>
 * Coordinates are infinitely thin and lie between the pixels of the
 * output device.
 * Operations that draw the outline of a figure operate by traversing
 * an infinitely thin path between pixels with a pixel-sized pen that hangs
 * down and to the right of the anchor point on the path.
 * Operations that fill a figure operate by filling the interior
 * of that infinitely thin path.
 * Operations that render horizontal text render the ascending
 * portion of character glyphs entirely above the baseline coordinate.
 * <p>
 * The graphics pen hangs down and to the right from the path it traverses.
 * This has the following implications:
 * <ul>
 * <li>If you draw a figure that covers a given rectangle, that
 * figure occupies one extra row of pixels on the right and bottom edges
 * as compared to filling a figure that is bounded by that same rectangle.
 * <li>If you draw a horizontal line along the same <i>y</i> coordinate as
 * the baseline of a line of text, that line is drawn entirely below
 * the text, except for any descenders.
 * </ul><p>
 * All coordinates that appear as arguments to the methods of this
 * <code>Graphics</code> object are considered relative to the
 * translation origin of this <code>Graphics</code> object prior to
 * the invocation of the method.
 * <p>
 * All rendering operations modify only pixels which lie within the
 * area bounded by the current clip, which is specified by a {@link Shape}
 * in user space and is controlled by the program using the
 * <code>Graphics</code> object.  This <i>user clip</i>
 * is transformed into device space and combined with the
 * <i>device clip</i>, which is defined by the visibility of windows and
 * device extents.  The combination of the user clip and device clip
 * defines the <i>composite clip</i>, which determines the final clipping
 * region.  The user clip cannot be modified by the rendering
 * system to reflect the resulting composite clip. The user clip can only
 * be changed through the <code>setClip</code> or <code>clipRect</code>
 * methods.
 * All drawing or writing is done in the current color,
 * using the current paint mode, and in the current font.
 *
 * @author Sami Shaio
 * @author Arthur van Hoff
 * @see java.awt.Component
 * @see java.awt.Graphics#clipRect(int, int, int, int)
 * @see java.awt.Graphics#setColor(java.awt.Color)
 * @see java.awt.Graphics#setPaintMode()
 * @see java.awt.Graphics#setXORMode(java.awt.Color)
 * @see java.awt.Graphics#setFont(java.awt.Font)
 * @since JDK1.0
 */
public abstract class Graphics {

  /**
   * Constructs a new <code>Graphics</code> object.
   * This constructor is the default constructor for a graphics
   * context.
   * <p>
   * Since <code>Graphics</code> is an abstract class, applications
   * cannot call this constructor directly. Graphics contexts are
   * obtained from other graphics contexts or are created by calling
   * <code>getGraphics</code> on a component.
   *
   * @see java.awt.Graphics#create()
   * @see java.awt.Component#getGraphics
   */
  protected Graphics() {
  }

  /**
   * Creates a new <code>Graphics</code> object that is
   * a copy of this <code>Graphics</code> object.
   *
   * @return a new graphics context that is a copy of this graphics context.
   */
  public abstract Graphics create();

  /**
   * Creates a new <code>Graphics</code> object based on this
   * <code>Graphics</code> object, but with a new translation and clip area.
   * The new <code>Graphics</code> object has its origin
   * translated to the specified point (<i>x</i>,&nbsp;<i>y</i>).
   * Its clip area is determined by the intersection of the original
   * clip area with the specified rectangle.  The arguments are all
   * interpreted in the coordinate system of the original
   * <code>Graphics</code> object. The new graphics context is
   * identical to the original, except in two respects:
   *
   * <ul>
   * <li>
   * The new graphics context is translated by (<i>x</i>,&nbsp;<i>y</i>).
   * That is to say, the point (<code>0</code>,&nbsp;<code>0</code>) in the
   * new graphics context is the same as (<i>x</i>,&nbsp;<i>y</i>) in
   * the original graphics context.
   * <li>
   * The new graphics context has an additional clipping rectangle, in
   * addition to whatever (translated) clipping rectangle it inherited
   * from the original graphics context. The origin of the new clipping
   * rectangle is at (<code>0</code>,&nbsp;<code>0</code>), and its size
   * is specified by the <code>width</code> and <code>height</code>
   * arguments.
   * </ul>
   * <p>
   *
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @param width the width of the clipping rectangle.
   * @param height the height of the clipping rectangle.
   * @return a new graphics context.
   * @see java.awt.Graphics#translate
   * @see java.awt.Graphics#clipRect
   */
  public Graphics create(int x, int y, int width, int height) {
    Graphics g = create();
    if (g == null) {
      return null;
    }
    g.translate(x, y);
    g.clipRect(0, 0, width, height);
    return g;
  }

  /**
   * Translates the origin of the graphics context to the point
   * (<i>x</i>,&nbsp;<i>y</i>) in the current coordinate system.
   * Modifies this graphics context so that its new origin corresponds
   * to the point (<i>x</i>,&nbsp;<i>y</i>) in this graphics context's
   * original coordinate system.  All coordinates used in subsequent
   * rendering operations on this graphics context will be relative
   * to this new origin.
   *
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   */
  public abstract void translate(int x, int y);

  /**
   * Gets this graphics context's current color.
   *
   * @return this graphics context's current color.
   * @see java.awt.Color
   * @see java.awt.Graphics#setColor(Color)
   */
  public abstract Color getColor();

  /**
   * Sets this graphics context's current color to the specified
   * color. All subsequent graphics operations using this graphics
   * context use this specified color.
   *
   * @param c the new rendering color.
   * @see java.awt.Color
   * @see java.awt.Graphics#getColor
   */
  public abstract void setColor(Color c);

  /**
   * Sets the paint mode of this graphics context to overwrite the
   * destination with this graphics context's current color.
   * This sets the logical pixel operation function to the paint or
   * overwrite mode.  All subsequent rendering operations will
   * overwrite the destination with the current color.
   */
  public abstract void setPaintMode();

  /**
   * Sets the paint mode of this graphics context to alternate between
   * this graphics context's current color and the new specified color.
   * This specifies that logical pixel operations are performed in the
   * XOR mode, which alternates pixels between the current color and
   * a specified XOR color.
   * <p>
   * When drawing operations are performed, pixels which are the
   * current color are changed to the specified color, and vice versa.
   * <p>
   * Pixels that are of colors other than those two colors are changed
   * in an unpredictable but reversible manner; if the same figure is
   * drawn twice, then all pixels are restored to their original values.
   *
   * @param c1 the XOR alternation color
   */
  public abstract void setXORMode(Color c1);

  /**
   * Gets the current font.
   *
   * @return this graphics context's current font.
   * @see java.awt.Font
   * @see java.awt.Graphics#setFont(Font)
   */
  public abstract Font getFont();

  /**
   * Sets this graphics context's font to the specified font.
   * All subsequent text operations using this graphics context
   * use this font. A null argument is silently ignored.
   *
   * @param font the font.
   * @see java.awt.Graphics#getFont
   * @see java.awt.Graphics#drawString(java.lang.String, int, int)
   * @see java.awt.Graphics#drawBytes(byte[], int, int, int, int)
   * @see java.awt.Graphics#drawChars(char[], int, int, int, int)
   */
  public abstract void setFont(Font font);

  /**
   * Gets the font metrics of the current font.
   *
   * @return the font metrics of this graphics context's current font.
   * @see java.awt.Graphics#getFont
   * @see java.awt.FontMetrics
   * @see java.awt.Graphics#getFontMetrics(Font)
   */
  public FontMetrics getFontMetrics() {
    return getFontMetrics(getFont());
  }

  /**
   * Gets the font metrics for the specified font.
   *
   * @param f the specified font
   * @return the font metrics for the specified font.
   * @see java.awt.Graphics#getFont
   * @see java.awt.FontMetrics
   * @see java.awt.Graphics#getFontMetrics()
   */
  public abstract FontMetrics getFontMetrics(Font f);


  /**
   * Returns the bounding rectangle of the current clipping area.
   * This method refers to the user clip, which is independent of the
   * clipping associated with device bounds and window visibility.
   * If no clip has previously been set, or if the clip has been
   * cleared using <code>setClip(null)</code>, this method returns
   * <code>null</code>.
   * The coordinates in the rectangle are relative to the coordinate
   * system origin of this graphics context.
   *
   * @return the bounding rectangle of the current clipping area, or <code>null</code> if no clip is
   * set.
   * @see java.awt.Graphics#getClip
   * @see java.awt.Graphics#clipRect
   * @see java.awt.Graphics#setClip(int, int, int, int)
   * @see java.awt.Graphics#setClip(Shape)
   * @since JDK1.1
   */
  public abstract Rectangle getClipBounds();

  /**
   * Intersects the current clip with the specified rectangle.
   * The resulting clipping area is the intersection of the current
   * clipping area and the specified rectangle.  If there is no
   * current clipping area, either because the clip has never been
   * set, or the clip has been cleared using <code>setClip(null)</code>,
   * the specified rectangle becomes the new clip.
   * This method sets the user clip, which is independent of the
   * clipping associated with device bounds and window visibility.
   * This method can only be used to make the current clip smaller.
   * To set the current clip larger, use any of the setClip methods.
   * Rendering operations have no effect outside of the clipping area.
   *
   * @param x the x coordinate of the rectangle to intersect the clip with
   * @param y the y coordinate of the rectangle to intersect the clip with
   * @param width the width of the rectangle to intersect the clip with
   * @param height the height of the rectangle to intersect the clip with
   * @see #setClip(int, int, int, int)
   * @see #setClip(Shape)
   */
  public abstract void clipRect(int x, int y, int width, int height);

  /**
   * Sets the current clip to the rectangle specified by the given
   * coordinates.  This method sets the user clip, which is
   * independent of the clipping associated with device bounds
   * and window visibility.
   * Rendering operations have no effect outside of the clipping area.
   *
   * @param x the <i>x</i> coordinate of the new clip rectangle.
   * @param y the <i>y</i> coordinate of the new clip rectangle.
   * @param width the width of the new clip rectangle.
   * @param height the height of the new clip rectangle.
   * @see java.awt.Graphics#clipRect
   * @see java.awt.Graphics#setClip(Shape)
   * @see java.awt.Graphics#getClip
   * @since JDK1.1
   */
  public abstract void setClip(int x, int y, int width, int height);

  /**
   * Gets the current clipping area.
   * This method returns the user clip, which is independent of the
   * clipping associated with device bounds and window visibility.
   * If no clip has previously been set, or if the clip has been
   * cleared using <code>setClip(null)</code>, this method returns
   * <code>null</code>.
   *
   * @return a <code>Shape</code> object representing the current clipping area, or
   * <code>null</code> if no clip is set.
   * @see java.awt.Graphics#getClipBounds
   * @see java.awt.Graphics#clipRect
   * @see java.awt.Graphics#setClip(int, int, int, int)
   * @see java.awt.Graphics#setClip(Shape)
   * @since JDK1.1
   */
  public abstract Shape getClip();

  /**
   * Sets the current clipping area to an arbitrary clip shape.
   * Not all objects that implement the <code>Shape</code>
   * interface can be used to set the clip.  The only
   * <code>Shape</code> objects that are guaranteed to be
   * supported are <code>Shape</code> objects that are
   * obtained via the <code>getClip</code> method and via
   * <code>Rectangle</code> objects.  This method sets the
   * user clip, which is independent of the clipping associated
   * with device bounds and window visibility.
   *
   * @param clip the <code>Shape</code> to use to set the clip
   * @see java.awt.Graphics#getClip()
   * @see java.awt.Graphics#clipRect
   * @see java.awt.Graphics#setClip(int, int, int, int)
   * @since JDK1.1
   */
  public abstract void setClip(Shape clip);

  /**
   * Copies an area of the component by a distance specified by
   * <code>dx</code> and <code>dy</code>. From the point specified
   * by <code>x</code> and <code>y</code>, this method
   * copies downwards and to the right.  To copy an area of the
   * component to the left or upwards, specify a negative value for
   * <code>dx</code> or <code>dy</code>.
   * If a portion of the source rectangle lies outside the bounds
   * of the component, or is obscured by another window or component,
   * <code>copyArea</code> will be unable to copy the associated
   * pixels. The area that is omitted can be refreshed by calling
   * the component's <code>paint</code> method.
   *
   * @param x the <i>x</i> coordinate of the source rectangle.
   * @param y the <i>y</i> coordinate of the source rectangle.
   * @param width the width of the source rectangle.
   * @param height the height of the source rectangle.
   * @param dx the horizontal distance to copy the pixels.
   * @param dy the vertical distance to copy the pixels.
   */
  public abstract void copyArea(int x, int y, int width, int height,
      int dx, int dy);

  /**
   * Draws a line, using the current color, between the points
   * <code>(x1,&nbsp;y1)</code> and <code>(x2,&nbsp;y2)</code>
   * in this graphics context's coordinate system.
   *
   * @param x1 the first point's <i>x</i> coordinate.
   * @param y1 the first point's <i>y</i> coordinate.
   * @param x2 the second point's <i>x</i> coordinate.
   * @param y2 the second point's <i>y</i> coordinate.
   */
  public abstract void drawLine(int x1, int y1, int x2, int y2);

  /**
   * Fills the specified rectangle.
   * The left and right edges of the rectangle are at
   * <code>x</code> and <code>x&nbsp;+&nbsp;width&nbsp;-&nbsp;1</code>.
   * The top and bottom edges are at
   * <code>y</code> and <code>y&nbsp;+&nbsp;height&nbsp;-&nbsp;1</code>.
   * The resulting rectangle covers an area
   * <code>width</code> pixels wide by
   * <code>height</code> pixels tall.
   * The rectangle is filled using the graphics context's current color.
   *
   * @param x the <i>x</i> coordinate of the rectangle to be filled.
   * @param y the <i>y</i> coordinate of the rectangle to be filled.
   * @param width the width of the rectangle to be filled.
   * @param height the height of the rectangle to be filled.
   * @see java.awt.Graphics#clearRect
   * @see java.awt.Graphics#drawRect
   */
  public abstract void fillRect(int x, int y, int width, int height);

  /**
   * Draws the outline of the specified rectangle.
   * The left and right edges of the rectangle are at
   * <code>x</code> and <code>x&nbsp;+&nbsp;width</code>.
   * The top and bottom edges are at
   * <code>y</code> and <code>y&nbsp;+&nbsp;height</code>.
   * The rectangle is drawn using the graphics context's current color.
   *
   * @param x the <i>x</i> coordinate of the rectangle to be drawn.
   * @param y the <i>y</i> coordinate of the rectangle to be drawn.
   * @param width the width of the rectangle to be drawn.
   * @param height the height of the rectangle to be drawn.
   * @see java.awt.Graphics#fillRect
   * @see java.awt.Graphics#clearRect
   */
  public void drawRect(int x, int y, int width, int height) {
    if ((width < 0) || (height < 0)) {
      return;
    }

    if (height == 0 || width == 0) {
      drawLine(x, y, x + width, y + height);
    } else {
      drawLine(x, y, x + width - 1, y);
      drawLine(x + width, y, x + width, y + height - 1);
      drawLine(x + width, y + height, x + 1, y + height);
      drawLine(x, y + height, x, y + 1);
    }
  }

  /**
   * Clears the specified rectangle by filling it with the background
   * color of the current drawing surface. This operation does not
   * use the current paint mode.
   * <p>
   * Beginning with Java&nbsp;1.1, the background color
   * of offscreen images may be system dependent. Applications should
   * use <code>setColor</code> followed by <code>fillRect</code> to
   * ensure that an offscreen image is cleared to a specific color.
   *
   * @param x the <i>x</i> coordinate of the rectangle to clear.
   * @param y the <i>y</i> coordinate of the rectangle to clear.
   * @param width the width of the rectangle to clear.
   * @param height the height of the rectangle to clear.
   * @see java.awt.Graphics#fillRect(int, int, int, int)
   * @see java.awt.Graphics#drawRect
   * @see java.awt.Graphics#setColor(java.awt.Color)
   * @see java.awt.Graphics#setPaintMode
   * @see java.awt.Graphics#setXORMode(java.awt.Color)
   */
  public abstract void clearRect(int x, int y, int width, int height);

  /**
   * Draws an outlined round-cornered rectangle using this graphics
   * context's current color. The left and right edges of the rectangle
   * are at <code>x</code> and <code>x&nbsp;+&nbsp;width</code>,
   * respectively. The top and bottom edges of the rectangle are at
   * <code>y</code> and <code>y&nbsp;+&nbsp;height</code>.
   *
   * @param x the <i>x</i> coordinate of the rectangle to be drawn.
   * @param y the <i>y</i> coordinate of the rectangle to be drawn.
   * @param width the width of the rectangle to be drawn.
   * @param height the height of the rectangle to be drawn.
   * @param arcWidth the horizontal diameter of the arc at the four corners.
   * @param arcHeight the vertical diameter of the arc at the four corners.
   * @see java.awt.Graphics#fillRoundRect
   */
  public abstract void drawRoundRect(int x, int y, int width, int height,
      int arcWidth, int arcHeight);

  /**
   * Fills the specified rounded corner rectangle with the current color.
   * The left and right edges of the rectangle
   * are at <code>x</code> and <code>x&nbsp;+&nbsp;width&nbsp;-&nbsp;1</code>,
   * respectively. The top and bottom edges of the rectangle are at
   * <code>y</code> and <code>y&nbsp;+&nbsp;height&nbsp;-&nbsp;1</code>.
   *
   * @param x the <i>x</i> coordinate of the rectangle to be filled.
   * @param y the <i>y</i> coordinate of the rectangle to be filled.
   * @param width the width of the rectangle to be filled.
   * @param height the height of the rectangle to be filled.
   * @param arcWidth the horizontal diameter of the arc at the four corners.
   * @param arcHeight the vertical diameter of the arc at the four corners.
   * @see java.awt.Graphics#drawRoundRect
   */
  public abstract void fillRoundRect(int x, int y, int width, int height,
      int arcWidth, int arcHeight);

  /**
   * Draws a 3-D highlighted outline of the specified rectangle.
   * The edges of the rectangle are highlighted so that they
   * appear to be beveled and lit from the upper left corner.
   * <p>
   * The colors used for the highlighting effect are determined
   * based on the current color.
   * The resulting rectangle covers an area that is
   * <code>width&nbsp;+&nbsp;1</code> pixels wide
   * by <code>height&nbsp;+&nbsp;1</code> pixels tall.
   *
   * @param x the <i>x</i> coordinate of the rectangle to be drawn.
   * @param y the <i>y</i> coordinate of the rectangle to be drawn.
   * @param width the width of the rectangle to be drawn.
   * @param height the height of the rectangle to be drawn.
   * @param raised a boolean that determines whether the rectangle appears to be raised above the
   * surface or sunk into the surface.
   * @see java.awt.Graphics#fill3DRect
   */
  public void draw3DRect(int x, int y, int width, int height,
      boolean raised) {
    Color c = getColor();
    Color brighter = c.brighter();
    Color darker = c.darker();

    setColor(raised ? brighter : darker);
    drawLine(x, y, x, y + height);
    drawLine(x + 1, y, x + width - 1, y);
    setColor(raised ? darker : brighter);
    drawLine(x + 1, y + height, x + width, y + height);
    drawLine(x + width, y, x + width, y + height - 1);
    setColor(c);
  }

  /**
   * Paints a 3-D highlighted rectangle filled with the current color.
   * The edges of the rectangle will be highlighted so that it appears
   * as if the edges were beveled and lit from the upper left corner.
   * The colors used for the highlighting effect will be determined from
   * the current color.
   *
   * @param x the <i>x</i> coordinate of the rectangle to be filled.
   * @param y the <i>y</i> coordinate of the rectangle to be filled.
   * @param width the width of the rectangle to be filled.
   * @param height the height of the rectangle to be filled.
   * @param raised a boolean value that determines whether the rectangle appears to be raised above
   * the surface or etched into the surface.
   * @see java.awt.Graphics#draw3DRect
   */
  public void fill3DRect(int x, int y, int width, int height,
      boolean raised) {
    Color c = getColor();
    Color brighter = c.brighter();
    Color darker = c.darker();

    if (!raised) {
      setColor(darker);
    }
    fillRect(x + 1, y + 1, width - 2, height - 2);
    setColor(raised ? brighter : darker);
    drawLine(x, y, x, y + height - 1);
    drawLine(x + 1, y, x + width - 2, y);
    setColor(raised ? darker : brighter);
    drawLine(x + 1, y + height - 1, x + width - 1, y + height - 1);
    drawLine(x + width - 1, y, x + width - 1, y + height - 2);
    setColor(c);
  }

  /**
   * Draws the outline of an oval.
   * The result is a circle or ellipse that fits within the
   * rectangle specified by the <code>x</code>, <code>y</code>,
   * <code>width</code>, and <code>height</code> arguments.
   * <p>
   * The oval covers an area that is
   * <code>width&nbsp;+&nbsp;1</code> pixels wide
   * and <code>height&nbsp;+&nbsp;1</code> pixels tall.
   *
   * @param x the <i>x</i> coordinate of the upper left corner of the oval to be drawn.
   * @param y the <i>y</i> coordinate of the upper left corner of the oval to be drawn.
   * @param width the width of the oval to be drawn.
   * @param height the height of the oval to be drawn.
   * @see java.awt.Graphics#fillOval
   */
  public abstract void drawOval(int x, int y, int width, int height);

  /**
   * Fills an oval bounded by the specified rectangle with the
   * current color.
   *
   * @param x the <i>x</i> coordinate of the upper left corner of the oval to be filled.
   * @param y the <i>y</i> coordinate of the upper left corner of the oval to be filled.
   * @param width the width of the oval to be filled.
   * @param height the height of the oval to be filled.
   * @see java.awt.Graphics#drawOval
   */
  public abstract void fillOval(int x, int y, int width, int height);

  /**
   * Draws the outline of a circular or elliptical arc
   * covering the specified rectangle.
   * <p>
   * The resulting arc begins at <code>startAngle</code> and extends
   * for <code>arcAngle</code> degrees, using the current color.
   * Angles are interpreted such that 0&nbsp;degrees
   * is at the 3&nbsp;o'clock position.
   * A positive value indicates a counter-clockwise rotation
   * while a negative value indicates a clockwise rotation.
   * <p>
   * The center of the arc is the center of the rectangle whose origin
   * is (<i>x</i>,&nbsp;<i>y</i>) and whose size is specified by the
   * <code>width</code> and <code>height</code> arguments.
   * <p>
   * The resulting arc covers an area
   * <code>width&nbsp;+&nbsp;1</code> pixels wide
   * by <code>height&nbsp;+&nbsp;1</code> pixels tall.
   * <p>
   * The angles are specified relative to the non-square extents of
   * the bounding rectangle such that 45 degrees always falls on the
   * line from the center of the ellipse to the upper right corner of
   * the bounding rectangle. As a result, if the bounding rectangle is
   * noticeably longer in one axis than the other, the angles to the
   * start and end of the arc segment will be skewed farther along the
   * longer axis of the bounds.
   *
   * @param x the <i>x</i> coordinate of the upper-left corner of the arc to be drawn.
   * @param y the <i>y</i>  coordinate of the upper-left corner of the arc to be drawn.
   * @param width the width of the arc to be drawn.
   * @param height the height of the arc to be drawn.
   * @param startAngle the beginning angle.
   * @param arcAngle the angular extent of the arc, relative to the start angle.
   * @see java.awt.Graphics#fillArc
   */
  public abstract void drawArc(int x, int y, int width, int height,
      int startAngle, int arcAngle);

  /**
   * Fills a circular or elliptical arc covering the specified rectangle.
   * <p>
   * The resulting arc begins at <code>startAngle</code> and extends
   * for <code>arcAngle</code> degrees.
   * Angles are interpreted such that 0&nbsp;degrees
   * is at the 3&nbsp;o'clock position.
   * A positive value indicates a counter-clockwise rotation
   * while a negative value indicates a clockwise rotation.
   * <p>
   * The center of the arc is the center of the rectangle whose origin
   * is (<i>x</i>,&nbsp;<i>y</i>) and whose size is specified by the
   * <code>width</code> and <code>height</code> arguments.
   * <p>
   * The resulting arc covers an area
   * <code>width&nbsp;+&nbsp;1</code> pixels wide
   * by <code>height&nbsp;+&nbsp;1</code> pixels tall.
   * <p>
   * The angles are specified relative to the non-square extents of
   * the bounding rectangle such that 45 degrees always falls on the
   * line from the center of the ellipse to the upper right corner of
   * the bounding rectangle. As a result, if the bounding rectangle is
   * noticeably longer in one axis than the other, the angles to the
   * start and end of the arc segment will be skewed farther along the
   * longer axis of the bounds.
   *
   * @param x the <i>x</i> coordinate of the upper-left corner of the arc to be filled.
   * @param y the <i>y</i>  coordinate of the upper-left corner of the arc to be filled.
   * @param width the width of the arc to be filled.
   * @param height the height of the arc to be filled.
   * @param startAngle the beginning angle.
   * @param arcAngle the angular extent of the arc, relative to the start angle.
   * @see java.awt.Graphics#drawArc
   */
  public abstract void fillArc(int x, int y, int width, int height,
      int startAngle, int arcAngle);

  /**
   * Draws a sequence of connected lines defined by
   * arrays of <i>x</i> and <i>y</i> coordinates.
   * Each pair of (<i>x</i>,&nbsp;<i>y</i>) coordinates defines a point.
   * The figure is not closed if the first point
   * differs from the last point.
   *
   * @param xPoints an array of <i>x</i> points
   * @param yPoints an array of <i>y</i> points
   * @param nPoints the total number of points
   * @see java.awt.Graphics#drawPolygon(int[], int[], int)
   * @since JDK1.1
   */
  public abstract void drawPolyline(int xPoints[], int yPoints[],
      int nPoints);

  /**
   * Draws a closed polygon defined by
   * arrays of <i>x</i> and <i>y</i> coordinates.
   * Each pair of (<i>x</i>,&nbsp;<i>y</i>) coordinates defines a point.
   * <p>
   * This method draws the polygon defined by <code>nPoint</code> line
   * segments, where the first <code>nPoint&nbsp;-&nbsp;1</code>
   * line segments are line segments from
   * <code>(xPoints[i&nbsp;-&nbsp;1],&nbsp;yPoints[i&nbsp;-&nbsp;1])</code>
   * to <code>(xPoints[i],&nbsp;yPoints[i])</code>, for
   * 1&nbsp;&le;&nbsp;<i>i</i>&nbsp;&le;&nbsp;<code>nPoints</code>.
   * The figure is automatically closed by drawing a line connecting
   * the final point to the first point, if those points are different.
   *
   * @param xPoints a an array of <code>x</code> coordinates.
   * @param yPoints a an array of <code>y</code> coordinates.
   * @param nPoints a the total number of points.
   * @see java.awt.Graphics#fillPolygon
   * @see java.awt.Graphics#drawPolyline
   */
  public abstract void drawPolygon(int xPoints[], int yPoints[],
      int nPoints);

  /**
   * Draws the outline of a polygon defined by the specified
   * <code>Polygon</code> object.
   *
   * @param p the polygon to draw.
   * @see java.awt.Graphics#fillPolygon
   * @see java.awt.Graphics#drawPolyline
   */
  public void drawPolygon(Polygon p) {
    drawPolygon(p.xpoints, p.ypoints, p.npoints);
  }

  /**
   * Fills a closed polygon defined by
   * arrays of <i>x</i> and <i>y</i> coordinates.
   * <p>
   * This method draws the polygon defined by <code>nPoint</code> line
   * segments, where the first <code>nPoint&nbsp;-&nbsp;1</code>
   * line segments are line segments from
   * <code>(xPoints[i&nbsp;-&nbsp;1],&nbsp;yPoints[i&nbsp;-&nbsp;1])</code>
   * to <code>(xPoints[i],&nbsp;yPoints[i])</code>, for
   * 1&nbsp;&le;&nbsp;<i>i</i>&nbsp;&le;&nbsp;<code>nPoints</code>.
   * The figure is automatically closed by drawing a line connecting
   * the final point to the first point, if those points are different.
   * <p>
   * The area inside the polygon is defined using an
   * even-odd fill rule, also known as the alternating rule.
   *
   * @param xPoints a an array of <code>x</code> coordinates.
   * @param yPoints a an array of <code>y</code> coordinates.
   * @param nPoints a the total number of points.
   * @see java.awt.Graphics#drawPolygon(int[], int[], int)
   */
  public abstract void fillPolygon(int xPoints[], int yPoints[],
      int nPoints);

  /**
   * Fills the polygon defined by the specified Polygon object with
   * the graphics context's current color.
   * <p>
   * The area inside the polygon is defined using an
   * even-odd fill rule, also known as the alternating rule.
   *
   * @param p the polygon to fill.
   * @see java.awt.Graphics#drawPolygon(int[], int[], int)
   */
  public void fillPolygon(Polygon p) {
    fillPolygon(p.xpoints, p.ypoints, p.npoints);
  }

  /**
   * Draws the text given by the specified string, using this
   * graphics context's current font and color. The baseline of the
   * leftmost character is at position (<i>x</i>,&nbsp;<i>y</i>) in this
   * graphics context's coordinate system.
   *
   * @param str the string to be drawn.
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @throws NullPointerException if <code>str</code> is <code>null</code>.
   * @see java.awt.Graphics#drawBytes
   * @see java.awt.Graphics#drawChars
   */
  public abstract void drawString(String str, int x, int y);

  /**
   * Renders the text of the specified iterator applying its attributes
   * in accordance with the specification of the
   * {@link java.awt.font.TextAttribute TextAttribute} class.
   * <p>
   * The baseline of the leftmost character is at position
   * (<i>x</i>,&nbsp;<i>y</i>) in this graphics context's coordinate system.
   *
   * @param iterator the iterator whose text is to be drawn
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @throws NullPointerException if <code>iterator</code> is <code>null</code>.
   * @see java.awt.Graphics#drawBytes
   * @see java.awt.Graphics#drawChars
   */
  public abstract void drawString(AttributedCharacterIterator iterator,
      int x, int y);

  /**
   * Draws the text given by the specified character array, using this
   * graphics context's current font and color. The baseline of the
   * first character is at position (<i>x</i>,&nbsp;<i>y</i>) in this
   * graphics context's coordinate system.
   *
   * @param data the array of characters to be drawn
   * @param offset the start offset in the data
   * @param length the number of characters to be drawn
   * @param x the <i>x</i> coordinate of the baseline of the text
   * @param y the <i>y</i> coordinate of the baseline of the text
   * @throws NullPointerException if <code>data</code> is <code>null</code>.
   * @throws IndexOutOfBoundsException if <code>offset</code> or <code>length</code>is less than
   * zero, or <code>offset+length</code> is greater than the length of the <code>data</code> array.
   * @see java.awt.Graphics#drawBytes
   * @see java.awt.Graphics#drawString
   */
  public void drawChars(char data[], int offset, int length, int x, int y) {
    drawString(new String(data, offset, length), x, y);
  }

  /**
   * Draws the text given by the specified byte array, using this
   * graphics context's current font and color. The baseline of the
   * first character is at position (<i>x</i>,&nbsp;<i>y</i>) in this
   * graphics context's coordinate system.
   * <p>
   * Use of this method is not recommended as each byte is interpreted
   * as a Unicode code point in the range 0 to 255, and so can only be
   * used to draw Latin characters in that range.
   *
   * @param data the data to be drawn
   * @param offset the start offset in the data
   * @param length the number of bytes that are drawn
   * @param x the <i>x</i> coordinate of the baseline of the text
   * @param y the <i>y</i> coordinate of the baseline of the text
   * @throws NullPointerException if <code>data</code> is <code>null</code>.
   * @throws IndexOutOfBoundsException if <code>offset</code> or <code>length</code>is less than
   * zero, or <code>offset+length</code> is greater than the length of the <code>data</code> array.
   * @see java.awt.Graphics#drawChars
   * @see java.awt.Graphics#drawString
   */
  public void drawBytes(byte data[], int offset, int length, int x, int y) {
    drawString(new String(data, 0, offset, length), x, y);
  }

  /**
   * Draws as much of the specified image as is currently available.
   * The image is drawn with its top-left corner at
   * (<i>x</i>,&nbsp;<i>y</i>) in this graphics context's coordinate
   * space. Transparent pixels in the image do not affect whatever
   * pixels are already there.
   * <p>
   * This method returns immediately in all cases, even if the
   * complete image has not yet been loaded, and it has not been dithered
   * and converted for the current output device.
   * <p>
   * If the image has completely loaded and its pixels are
   * no longer being changed, then
   * <code>drawImage</code> returns <code>true</code>.
   * Otherwise, <code>drawImage</code> returns <code>false</code>
   * and as more of
   * the image becomes available
   * or it is time to draw another frame of animation,
   * the process that loads the image notifies
   * the specified image observer.
   *
   * @param img the specified image to be drawn. This method does nothing if <code>img</code> is
   * null.
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @param observer object to be notified as more of the image is converted.
   * @return <code>false</code> if the image pixels are still changing; <code>true</code> otherwise.
   * @see java.awt.Image
   * @see java.awt.image.ImageObserver
   * @see java.awt.image.ImageObserver#imageUpdate(java.awt.Image, int, int, int, int, int)
   */
  public abstract boolean drawImage(Image img, int x, int y,
      ImageObserver observer);

  /**
   * Draws as much of the specified image as has already been scaled
   * to fit inside the specified rectangle.
   * <p>
   * The image is drawn inside the specified rectangle of this
   * graphics context's coordinate space, and is scaled if
   * necessary. Transparent pixels do not affect whatever pixels
   * are already there.
   * <p>
   * This method returns immediately in all cases, even if the
   * entire image has not yet been scaled, dithered, and converted
   * for the current output device.
   * If the current output representation is not yet complete, then
   * <code>drawImage</code> returns <code>false</code>. As more of
   * the image becomes available, the process that loads the image notifies
   * the image observer by calling its <code>imageUpdate</code> method.
   * <p>
   * A scaled version of an image will not necessarily be
   * available immediately just because an unscaled version of the
   * image has been constructed for this output device.  Each size of
   * the image may be cached separately and generated from the original
   * data in a separate image production sequence.
   *
   * @param img the specified image to be drawn. This method does nothing if <code>img</code> is
   * null.
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @param width the width of the rectangle.
   * @param height the height of the rectangle.
   * @param observer object to be notified as more of the image is converted.
   * @return <code>false</code> if the image pixels are still changing; <code>true</code> otherwise.
   * @see java.awt.Image
   * @see java.awt.image.ImageObserver
   * @see java.awt.image.ImageObserver#imageUpdate(java.awt.Image, int, int, int, int, int)
   */
  public abstract boolean drawImage(Image img, int x, int y,
      int width, int height,
      ImageObserver observer);

  /**
   * Draws as much of the specified image as is currently available.
   * The image is drawn with its top-left corner at
   * (<i>x</i>,&nbsp;<i>y</i>) in this graphics context's coordinate
   * space.  Transparent pixels are drawn in the specified
   * background color.
   * <p>
   * This operation is equivalent to filling a rectangle of the
   * width and height of the specified image with the given color and then
   * drawing the image on top of it, but possibly more efficient.
   * <p>
   * This method returns immediately in all cases, even if the
   * complete image has not yet been loaded, and it has not been dithered
   * and converted for the current output device.
   * <p>
   * If the image has completely loaded and its pixels are
   * no longer being changed, then
   * <code>drawImage</code> returns <code>true</code>.
   * Otherwise, <code>drawImage</code> returns <code>false</code>
   * and as more of
   * the image becomes available
   * or it is time to draw another frame of animation,
   * the process that loads the image notifies
   * the specified image observer.
   *
   * @param img the specified image to be drawn. This method does nothing if <code>img</code> is
   * null.
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @param bgcolor the background color to paint under the non-opaque portions of the image.
   * @param observer object to be notified as more of the image is converted.
   * @return <code>false</code> if the image pixels are still changing; <code>true</code> otherwise.
   * @see java.awt.Image
   * @see java.awt.image.ImageObserver
   * @see java.awt.image.ImageObserver#imageUpdate(java.awt.Image, int, int, int, int, int)
   */
  public abstract boolean drawImage(Image img, int x, int y,
      Color bgcolor,
      ImageObserver observer);

  /**
   * Draws as much of the specified image as has already been scaled
   * to fit inside the specified rectangle.
   * <p>
   * The image is drawn inside the specified rectangle of this
   * graphics context's coordinate space, and is scaled if
   * necessary. Transparent pixels are drawn in the specified
   * background color.
   * This operation is equivalent to filling a rectangle of the
   * width and height of the specified image with the given color and then
   * drawing the image on top of it, but possibly more efficient.
   * <p>
   * This method returns immediately in all cases, even if the
   * entire image has not yet been scaled, dithered, and converted
   * for the current output device.
   * If the current output representation is not yet complete then
   * <code>drawImage</code> returns <code>false</code>. As more of
   * the image becomes available, the process that loads the image notifies
   * the specified image observer.
   * <p>
   * A scaled version of an image will not necessarily be
   * available immediately just because an unscaled version of the
   * image has been constructed for this output device.  Each size of
   * the image may be cached separately and generated from the original
   * data in a separate image production sequence.
   *
   * @param img the specified image to be drawn. This method does nothing if <code>img</code> is
   * null.
   * @param x the <i>x</i> coordinate.
   * @param y the <i>y</i> coordinate.
   * @param width the width of the rectangle.
   * @param height the height of the rectangle.
   * @param bgcolor the background color to paint under the non-opaque portions of the image.
   * @param observer object to be notified as more of the image is converted.
   * @return <code>false</code> if the image pixels are still changing; <code>true</code> otherwise.
   * @see java.awt.Image
   * @see java.awt.image.ImageObserver
   * @see java.awt.image.ImageObserver#imageUpdate(java.awt.Image, int, int, int, int, int)
   */
  public abstract boolean drawImage(Image img, int x, int y,
      int width, int height,
      Color bgcolor,
      ImageObserver observer);

  /**
   * Draws as much of the specified area of the specified image as is
   * currently available, scaling it on the fly to fit inside the
   * specified area of the destination drawable surface. Transparent pixels
   * do not affect whatever pixels are already there.
   * <p>
   * This method returns immediately in all cases, even if the
   * image area to be drawn has not yet been scaled, dithered, and converted
   * for the current output device.
   * If the current output representation is not yet complete then
   * <code>drawImage</code> returns <code>false</code>. As more of
   * the image becomes available, the process that loads the image notifies
   * the specified image observer.
   * <p>
   * This method always uses the unscaled version of the image
   * to render the scaled rectangle and performs the required
   * scaling on the fly. It does not use a cached, scaled version
   * of the image for this operation. Scaling of the image from source
   * to destination is performed such that the first coordinate
   * of the source rectangle is mapped to the first coordinate of
   * the destination rectangle, and the second source coordinate is
   * mapped to the second destination coordinate. The subimage is
   * scaled and flipped as needed to preserve those mappings.
   *
   * @param img the specified image to be drawn. This method does nothing if <code>img</code> is
   * null.
   * @param dx1 the <i>x</i> coordinate of the first corner of the destination rectangle.
   * @param dy1 the <i>y</i> coordinate of the first corner of the destination rectangle.
   * @param dx2 the <i>x</i> coordinate of the second corner of the destination rectangle.
   * @param dy2 the <i>y</i> coordinate of the second corner of the destination rectangle.
   * @param sx1 the <i>x</i> coordinate of the first corner of the source rectangle.
   * @param sy1 the <i>y</i> coordinate of the first corner of the source rectangle.
   * @param sx2 the <i>x</i> coordinate of the second corner of the source rectangle.
   * @param sy2 the <i>y</i> coordinate of the second corner of the source rectangle.
   * @param observer object to be notified as more of the image is scaled and converted.
   * @return <code>false</code> if the image pixels are still changing; <code>true</code> otherwise.
   * @see java.awt.Image
   * @see java.awt.image.ImageObserver
   * @see java.awt.image.ImageObserver#imageUpdate(java.awt.Image, int, int, int, int, int)
   * @since JDK1.1
   */
  public abstract boolean drawImage(Image img,
      int dx1, int dy1, int dx2, int dy2,
      int sx1, int sy1, int sx2, int sy2,
      ImageObserver observer);

  /**
   * Draws as much of the specified area of the specified image as is
   * currently available, scaling it on the fly to fit inside the
   * specified area of the destination drawable surface.
   * <p>
   * Transparent pixels are drawn in the specified background color.
   * This operation is equivalent to filling a rectangle of the
   * width and height of the specified image with the given color and then
   * drawing the image on top of it, but possibly more efficient.
   * <p>
   * This method returns immediately in all cases, even if the
   * image area to be drawn has not yet been scaled, dithered, and converted
   * for the current output device.
   * If the current output representation is not yet complete then
   * <code>drawImage</code> returns <code>false</code>. As more of
   * the image becomes available, the process that loads the image notifies
   * the specified image observer.
   * <p>
   * This method always uses the unscaled version of the image
   * to render the scaled rectangle and performs the required
   * scaling on the fly. It does not use a cached, scaled version
   * of the image for this operation. Scaling of the image from source
   * to destination is performed such that the first coordinate
   * of the source rectangle is mapped to the first coordinate of
   * the destination rectangle, and the second source coordinate is
   * mapped to the second destination coordinate. The subimage is
   * scaled and flipped as needed to preserve those mappings.
   *
   * @param img the specified image to be drawn. This method does nothing if <code>img</code> is
   * null.
   * @param dx1 the <i>x</i> coordinate of the first corner of the destination rectangle.
   * @param dy1 the <i>y</i> coordinate of the first corner of the destination rectangle.
   * @param dx2 the <i>x</i> coordinate of the second corner of the destination rectangle.
   * @param dy2 the <i>y</i> coordinate of the second corner of the destination rectangle.
   * @param sx1 the <i>x</i> coordinate of the first corner of the source rectangle.
   * @param sy1 the <i>y</i> coordinate of the first corner of the source rectangle.
   * @param sx2 the <i>x</i> coordinate of the second corner of the source rectangle.
   * @param sy2 the <i>y</i> coordinate of the second corner of the source rectangle.
   * @param bgcolor the background color to paint under the non-opaque portions of the image.
   * @param observer object to be notified as more of the image is scaled and converted.
   * @return <code>false</code> if the image pixels are still changing; <code>true</code> otherwise.
   * @see java.awt.Image
   * @see java.awt.image.ImageObserver
   * @see java.awt.image.ImageObserver#imageUpdate(java.awt.Image, int, int, int, int, int)
   * @since JDK1.1
   */
  public abstract boolean drawImage(Image img,
      int dx1, int dy1, int dx2, int dy2,
      int sx1, int sy1, int sx2, int sy2,
      Color bgcolor,
      ImageObserver observer);

  /**
   * Disposes of this graphics context and releases
   * any system resources that it is using.
   * A <code>Graphics</code> object cannot be used after
   * <code>dispose</code>has been called.
   * <p>
   * When a Java program runs, a large number of <code>Graphics</code>
   * objects can be created within a short time frame.
   * Although the finalization process of the garbage collector
   * also disposes of the same system resources, it is preferable
   * to manually free the associated resources by calling this
   * method rather than to rely on a finalization process which
   * may not run to completion for a long period of time.
   * <p>
   * Graphics objects which are provided as arguments to the
   * <code>paint</code> and <code>update</code> methods
   * of components are automatically released by the system when
   * those methods return. For efficiency, programmers should
   * call <code>dispose</code> when finished using
   * a <code>Graphics</code> object only if it was created
   * directly from a component or another <code>Graphics</code> object.
   *
   * @see java.awt.Graphics#finalize
   * @see java.awt.Component#paint
   * @see java.awt.Component#update
   * @see java.awt.Component#getGraphics
   * @see java.awt.Graphics#create
   */
  public abstract void dispose();

  /**
   * Disposes of this graphics context once it is no longer referenced.
   *
   * @see #dispose
   */
  public void finalize() {
    dispose();
  }

  /**
   * Returns a <code>String</code> object representing this
   * <code>Graphics</code> object's value.
   *
   * @return a string representation of this graphics context.
   */
  public String toString() {
    return getClass().getName() + "[font=" + getFont() + ",color=" + getColor() + "]";
  }

  /**
   * Returns the bounding rectangle of the current clipping area.
   *
   * @return the bounding rectangle of the current clipping area or <code>null</code> if no clip is
   * set.
   * @deprecated As of JDK version 1.1, replaced by <code>getClipBounds()</code>.
   */
  @Deprecated
  public Rectangle getClipRect() {
    return getClipBounds();
  }

  /**
   * Returns true if the specified rectangular area might intersect
   * the current clipping area.
   * The coordinates of the specified rectangular area are in the
   * user coordinate space and are relative to the coordinate
   * system origin of this graphics context.
   * This method may use an algorithm that calculates a result quickly
   * but which sometimes might return true even if the specified
   * rectangular area does not intersect the clipping area.
   * The specific algorithm employed may thus trade off accuracy for
   * speed, but it will never return false unless it can guarantee
   * that the specified rectangular area does not intersect the
   * current clipping area.
   * The clipping area used by this method can represent the
   * intersection of the user clip as specified through the clip
   * methods of this graphics context as well as the clipping
   * associated with the device or image bounds and window visibility.
   *
   * @param x the x coordinate of the rectangle to test against the clip
   * @param y the y coordinate of the rectangle to test against the clip
   * @param width the width of the rectangle to test against the clip
   * @param height the height of the rectangle to test against the clip
   * @return <code>true</code> if the specified rectangle intersects the bounds of the current clip;
   * <code>false</code> otherwise.
   */
  public boolean hitClip(int x, int y, int width, int height) {
    // Note, this implementation is not very efficient.
    // Subclasses should override this method and calculate
    // the results more directly.
    Rectangle clipRect = getClipBounds();
    if (clipRect == null) {
      return true;
    }
    return clipRect.intersects(x, y, width, height);
  }

  /**
   * Returns the bounding rectangle of the current clipping area.
   * The coordinates in the rectangle are relative to the coordinate
   * system origin of this graphics context.  This method differs
   * from {@link #getClipBounds() getClipBounds} in that an existing
   * rectangle is used instead of allocating a new one.
   * This method refers to the user clip, which is independent of the
   * clipping associated with device bounds and window visibility.
   * If no clip has previously been set, or if the clip has been
   * cleared using <code>setClip(null)</code>, this method returns the
   * specified <code>Rectangle</code>.
   *
   * @param r the rectangle where the current clipping area is copied to.  Any current values in
   * this rectangle are overwritten.
   * @return the bounding rectangle of the current clipping area.
   */
  public Rectangle getClipBounds(Rectangle r) {
    // Note, this implementation is not very efficient.
    // Subclasses should override this method and avoid
    // the allocation overhead of getClipBounds().
    Rectangle clipRect = getClipBounds();
    if (clipRect != null) {
      r.x = clipRect.x;
      r.y = clipRect.y;
      r.width = clipRect.width;
      r.height = clipRect.height;
    } else if (r == null) {
      throw new NullPointerException("null rectangle parameter");
    }
    return r;
  }
}
